package com.my.framework.utils;

import com.my.framework.exception.ServiceException;
import org.apache.commons.lang3.Validate;
import org.apache.commons.lang3.exception.ExceptionUtils;

import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

/**
 * Created by mabo-pc on 2017-08-03.
 */
public class Digests {
	private static final String SHA1 = "SHA-1";
	private static final String MD5 = "MD5";
	private static SecureRandom random = new SecureRandom();

	public Digests() {
	}

	public static byte[] sha1(byte[] input) {
		return digest(input, "SHA-1", (byte[])null, 1);
	}

	public static byte[] sha1(byte[] input, byte[] salt) {
		return digest(input, "SHA-1", salt, 1);
	}

	public static byte[] sha1(byte[] input, byte[] salt, int iterations) {
		return digest(input, "SHA-1", salt, iterations);
	}

	private static byte[] digest(byte[] input, String algorithm, byte[] salt, int iterations) {
		try {
			MessageDigest e = MessageDigest.getInstance(algorithm);
			if(salt != null) {
				e.update(salt);
			}

			byte[] result = e.digest(input);

			for(int i = 1; i < iterations; ++i) {
				e.reset();
				result = e.digest(result);
			}

			return result;
		} catch (GeneralSecurityException var7) {
			throw ServiceException.unchecked(var7);
		}
	}

	public static byte[] generateSalt(int numBytes) {
		Validate.isTrue(numBytes > 0, "numBytes argument must be a positive integer (1 or larger)", (long)numBytes);
		byte[] bytes = new byte[numBytes];
		random.nextBytes(bytes);
		return bytes;
	}

	public static byte[] md5(InputStream input) throws IOException {
		return digest(input, "MD5");
	}

	public static byte[] sha1(InputStream input) throws IOException {
		return digest(input, "SHA-1");
	}

	private static byte[] digest(InputStream input, String algorithm) throws IOException {
		try {
			MessageDigest e = MessageDigest.getInstance(algorithm);
			short bufferLength = 8192;
			byte[] buffer = new byte[bufferLength];

			for(int read = input.read(buffer, 0, bufferLength); read > -1; read = input.read(buffer, 0, bufferLength)) {
				e.update(buffer, 0, read);
			}

			return e.digest();
		} catch (GeneralSecurityException var6) {
			throw ServiceException.unchecked(var6);
		}
	}
}